Trapping a click event for a programmatically generated context menu sub-menu

Question

I am trying to catch a click event on a context menu submenu created dynamically by the following code. The context menu cmList is created in the designer, and the click event code is added from the properties menu.

for (int i = 0; i <= sTagsContext.GetUpperBound(0); i++)
{
    cmListTags.Items.Add(sTagsContext[i]);
    ToolStripMenuItem submenu = new ToolStripMenuItem();                  
    submenu.Text = i.ToString();
    submenu.Image = Properties.Resources.InfoBig;

    (cmListTags.Items[i] as ToolStripMenuItem).DropDownItems.Add(submenu);                    
     chkListTags.ContextMenuStrip = cmListTags;
}

How can I create code to be executed when the submenu of any of the context menu items is clicked and have the identity of the submenu item (set in the text property) available?

I have tried adding an event handler using

(cmListTags.Items[i] as ToolStripMenuItem).DropDownItems.Add(i.ToString(), Properties.Resources.InfoBig, new EventHandler(InfoClicked));

where I create the function

public void InfoClicked(object sender, EventArgs e)
{
}

This function is called when the sub-menu is clicked but neither sender nor e has any information about the sub-menu item clicked - sender is null and e is empty.

If I set e to be type ToolStripItemClickedEventArgs and change the Dropdown addition line to

(cmListTags.Items[i] as ToolStripMenuItem).DropDownItems.Add(i.ToString(), Properties.Resources.InfoBig, new ToolStripItemClickedEventHandler(InfoClicked));

I get a compile time type mismatch for the last parameter of DropDownItems.Add.

I have edited you code and remove a seemingly redundant line, please check. — kennyzx
– kennyzx, Commented Oct 30, 2018 at 5:12

kennyzx · Accepted Answer · 2018-10-30 05:54:27Z

1

You can use an anonymous method - a method body without a name.

int index = i;
cmListTags.Items[i] as ToolStripMenuItem).DropDownItems.Add(
     i.ToString(), 
     Properties.Resources.InfoBig, 
     (s, args) => {
         MessageBox.Show(index.ToString(); 
} ));

Since the anonymous method is declared in place, it has access to the local variable i. So in this way you don't need to use sender.

Edit: Turns out i is being modified in the for loop. So I have to use a local copy index to keep its value.

And as to your 2nd question,

I get a compile time type mismatch for the last parameter of DropDownItems.Add.

This is because the signature of InfoClicked does not match the signature of delegate ToolStripItemClickedEventHandler.

edited Oct 30, 2018 at 5:54

answered Oct 30, 2018 at 5:33

kennyzx

13.1k6 gold badges41 silver badges87 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

SimonKravis Over a year ago

This is great - works fine. I replaced MessageBox.Show with code to show help depending on which submenu was clicked to. Many thanks.

Collectives™ on Stack Overflow

Trapping a click event for a programmatically generated context menu sub-menu

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related